Mortals with beasts selection questions.

The Army book doesn't really address this, or maybe i just didn't see it. But, hypothetically:

Say you have a mortal chaos army with beast's of chaos Allies, you've got your core mortals, but you also want chaos trolls or chaos ogres. Would they fill up a special selection? or can i not take them because they are not in the core units section of the BoC army book? Say i also want to take a unit of Dragon Ogres (or a shaggoth), would that be a rare selection for my army, would that not be allowed, or would that be a special selection?

PS. if an admin thinks this would be better answered in the beasts of chaos forum, please move it.

This isn't to insult anyone's intelligence, but to clarify everything, here's a definitive list of what is what:

Special units from the Beasts book are special, and Rare units from the Beasts book are rare, regardless of whether your army is Mortal, Daemon or Beast.

The generals are defined as follows;
If the character has the Daemonic special rule (regardless of the reasons why he has that rule) then he is a Daemonic general.
If the character is a model from the Beasts book, then he is a Beasts general (this of course, includes Shaggoth Champions).
Any other characters will be Mortal generals.